Field of the Invention
The present invention relates to a feeding device and an image forming apparatus.
Description of the Related Art
There have hitherto been image forming apparatuses, such as a copying machine, a printer, and a facsimile, including a sheet feeding device that supplies sheets to an image forming section. The sheet feeding device includes a sheet container unit that contains sheets to be fed. An example of such a sheet container unit is a feeding cassette detachably mounted in an image forming apparatus.
FIG. 19 illustrates a feeding cassette disclosed in Japanese Patent Laid-Open No. 2013-10611. In a feeding cassette 900, an intermediate plate 901 is provided pivotally on a pivot shaft 903a relative to a casing 903 in the upward and downward directions. A lifting plate 902 pushes up a downstream side of the intermediate plate 901 in a sheet feeding direction. Thus, sheets on the intermediate plate 901 are brought into contact with a pickup roller (feed roller) 904 with a predetermined pressing force. Sheets S pushed up by the intermediate plate 901 are fed out in a stable state by the pickup roller 904 and a conveying roller 905 downstream thereof. Then, images are formed on the sheets S conveyed from the feeding cassette 900.
As the market needs, there has recently been a strong demand to shorten the first print output time (FPOT) of the image forming apparatus. Further, from the viewpoint of usability, it is particularly effective to shorten the FPOT of the image forming apparatus. To shorten the FPOT under such circumstances, one problem is how to shorten the time required to convey a sheet to the image forming section after a print command is received from a personal computer or the like. For this reason, the image forming apparatus is preferably on standby with the pickup roller and the sheet being in contact with each other at the time when the print command is received.
On the other hand, in the market, there is a demand for an image forming apparatus that can use various types of sheets including thin paper having a basis weight of about 50 g/m2 and glossy paper for obtaining a high-quality print.
Among various types of sheets, there is a sheet that locally deforms or a sheet that changes in surface property in a portion in contact with the pickup roller when the standby state in which the pickup roller and the sheet are in contact continues for a long time (for example, one day or more). As a result, these may cause image defects.